The invention concerns elevator systems in general and, in particular, hall call registering and indicating apparatus located at elevator entryways.
A hall call registering and indicating apparatus having an indicating field with several indicating elements is shown in the European patent document EP-A 0 320 583. A first indicating element signals the selected destination floor in the form of a one-digit or two-digit decimal number and a second indicating element signals the allocated elevator in the shape of a capital letter. Further indicating elements signal a faulty call entry in the shape of a double question mark and the position of the allocated elevator relative to the actuated apparatus in the form of arrows directed to the left or to the right. The indicating elements are activated upon the call entry and call allocation by means of control circuits which are connected with a decade keyboard and with call storage devices connected to the decade keyboard and to a group control circuit. The indicating elements are formed of luminescent diodes which light up upon their activation and extinguish again after approximately two seconds.
Call registering and indicating apparatus of the kind described above are designed for group control equipment for elevators for which no call buttons are provided in the elevator cars. In such a group control circuit, which is shown in the European patent document EP-A 0 356 731, a call identifying the input floor and a call identifying the destination floor are stored for each elevator of the group upon the call entry at the input floor. Each elevator control includes a computer in the form of a microprocessor and a comparison device. Immediately after the registration of a call, the computer computes a sum, also called operating costs, corresponding to the mean waiting time of all passengers from data specific to the elevator. During an immediately following comparison of the operating costs of all elevators, the elevator with the lowest operating costs is ascertained, to which the call concerned is then allocated. As already described above, the allocated elevator is signaled optically for a short time in the indicating field of the actuated call registering and indicating apparatus. Inattentive waiting passengers or waiting passengers, for example, conducting a conversation can in that case overlook the indication or, when the indication was perceived only fleetingly, forget it again. If a different elevator traveling in the same direction is now used by mistake by the passenger, the probability is great that the desired destination floor is not reached. Since the indication must be present for a longer time to reduce the probability of such errors, for example one to two seconds, the performance capability of the call registering and indicating apparatus can be reduced greatly when used by a large number of passengers.